starting problems

[Martyn]

Twice I have not been able to start the car. On both occasions the weather has been hot 35C + in shade (Spain), I guess 40C+ in sun. The car is normally garaged and starts OK. However, on both occasions I drove for 20 miles or so, parked, no shade and it wouldn't start after leaving it for maybe two hours.

I thought it was due to my continuing dirty fuel tank problem (I have new one yet to install). The first time it happened I was towed home. Car was garaged and started the next day.

On the second occasion it happened another classic car owner suggested it was fuel evaporation due to the heat. We pushed it in the shade, opened the bonnet (hood). After a few minutes it started!

Not sure about the evaporation idea as fuel pump should overcome that (shouldn't it?). But can heat cause starting problems with the FI system?

Any suggestions would be a great help.

[Funcar]

I am not sure if this will help but an easy suggestion to try. Loosen the gas cap when you park. Do you get a woosh of fuel vapor?

[Martyn]

Its a weekend car so will try in a week. Thanks

[SteinOnkel]

Generally speaking, on an FI car fuel evaporation should not be an issue. It has no bowl to sit in and the pump produces somewhere to the tune of 40psi. More than ample to compress any air bubbles.

I would check your sensors. Not sure what these are on a Bosch L-Jet, not exactly my forte. I've seen hall pickups that have what feels like 10000 conditions between "works" and "it's broken". We've had cars that would fire up great at 0C, but at 30C forget it. Ditto for temperature sensors.

Next time it doesn't start when it's hot outside, pull a spark plug and see if you have spark. Also pull an injector and see if you have fuel. That should help narrow it down.

Here check this out:

http://www.njfiats.org/joomla/images/st ... ay2002.pdf

There should be a troubleshooting guide in there as well.

[Martyn]

Very interesting and great link also. Thanks for that.

The first time it happened I did pull a spark plug and got a spark and therefore assumed it was fuel. But I didn't do the injector test.

On the second time I didnt test but just cooled the car and it started. I guess it would have failed the injector test initially.

Further reading required. Thanks again.

[76was124]

Check the coolant temp sensor on the coolant manifold T at the head behind the radiator. Also have seen similar issues from ignition switch problems. Grab the bundle of wires at the back of the ignition switch and shift/lift them a lttle next time it won't start. If it's the ignition switch, add a starter relay, which reduces the wear and tear on the ignition switch by putting the full starter current going through the relay contacts.


See RRoller post , 2nd link.

Yes, the injectors fire by grounding. Per the manuals. Need those "noid lamps" that can rad the small signal and flash. (I think that is what they are called. )

Here are some great manuals:

FUEL INJECTION DEBUGGING
http://www.hiperformancestore.com/Ljetronic.htm
http://www.njfiats.org/joomla/images/st ... BoschL.pdf

FUEL INJECTOR CLEANING:
http://WWW.OKINJECTORS.COM
http://www.witchhunter.com

FUEL INJECTION MANUAL
http://www.mirafiori.com/faq/fiatFI_may2002.pdf

FUEL INJECTORS CHART
http://users.erols.com/srweiss/tableifc.htm

L-JETRONIC MANUAL
http://www.hiperformancestore.com/Ljetronic.htm

L-JETRONIC
http://mastertechmag.com/pdf/1988/11nov ... ronic2.pdf
http://jenniskens.livedsl.nl/Technical/ ... tronic.pdf

L-JETRONIC FI MANUAL (FROM VW)
https://www.type4.org/manuals/ljet/index.html

BOSCH L-JETRONIC MANUAL – BEST ONE:
http://foxed.ca/rx7manual/manuals/BOSCH ... Manual.pdf

http://dtec.net.au/Tech%20Articles.htm

[Martyn]

Thanks great list of links.

I have a new coolant temp sensor but not installed yet. One of my tasks is to renew cooling system items - pump, hoses, heater valve etc.

When the issue happens, the engine does turn over but doesnt start so not sure about the ignition switch possibility or am I showing my ignorance?

Martyn

[76was124]

No, sorry, I missed that it cranks, so not likely the ignition switch.

[GeorgeT]

Possibly the double relay is failing. I had a similar issue with my '82 and it had to completely fail before I could figure it out.

[tima01864]

TPS out of adjustment?

[76was124]

Good post on thermo time switch
http://www.fiatspider.com/f15/viewtopic ... ch#p282515

[tima01864]

that is the thermal time switch, I was referring to thr throttle posing switch. Is the black box attached to the throttle. Two screws on on top one on bottom. Try loosening the screws and a ccw turn, resetting by listening for a click or using an ohm meter. Is documented.

[micbrody]

I have 1981 FI.
On days when car has been sitting for enough time in garage to be at ambient temperature (65 deg F in summer; or 45 deg F in winter, the car starts immediately.
Especially in summer: if I start car and take a trip for at least 10 minutes; shut off car; and then try to start it again (usually when car is still warm or has been baking in sun, it has difficulty starting.
I have tested and adjusted everything but finally figured out issue (with help from the board):
Bad Thermo timing switch (TTS) that is stuck with power on all the time, regardless of coolant temperature.

The purpose of TTS is to fire 5th injector (Cold Start Injector) into intake manifold during the start of engine, but only for a certain amount of time depending on how the cold the engine is at start. It can fire up to 6-10 seconds when car outside in winter; but when car just slightly cold (65 deg F) , it’s only suppose to fire the CSI for a quick second (guessing rough times). The way the timing is adjusted is by some sort of bimetallic internal switch that deflects when heated by an internal heating coil AND temperature of coolant until the contact is broken; and electric circuit to CSI then stops. So when car is cold , it takes time for the internal heating coil to heat up bimetallic strip to eventually cause circuit interruption to CSI. If car has already been driven and coolant warm, the heat of coolant is enough to bend the bimetallic strip to open circuit, so CSI doesn’t fire at start up.
The issue is bad TTS in which bimetallic switch is permanently frozen in closed circuit position.
So on hot car start, the fuel mixture is too rich for easy start because CSI is spraying fuel when engine doesn’t need it.
To test this on your car: after driving car and engine still relatively warm, disconnect the electrical harness to CSI. This will prevent CSI to fire regardless of TTS. I did this; and on my car the hot starts are literally immediately.
Now if you leave it disconnected , you will notice that it is hard to start cold car because no extra fuel injection from CSI.
On my car I just leave harness disconnected, and only first start of day difficult.
I have not swapped out TTS yet. Unfortunately a few issues:
1) can be expensive part ($120???)
2) very difficult location: I think I need to jack up car and not sure even that will help. I might need to disconnect fuel rail and fuel injectors to get to from above if I can’t get from below
3) I have to first drain coolant (I think) because I believe all the coolant will leak out when I remove TTS.
I plan to try next time I flush radiator

[76was124]

that is the thermal time switch, I was referring to thr throttle posing switch.

. Understood, tps, but I put that link in related to the tts, in reference to my earlier post

[Martyn]

Thanks for all responses.

I plan to use the car next Sunday. As its ferociously hot here (Spain) its ideal conditions to test the TTS suggestion. I will do some research this week as I'm feeling a little out of my depth re fuel system and need to understand what I'm doing. But, hey, if all else fails there's always the tow truck (the Grua here) - its included with the car insurance!!!